Bio-electrode composition, bio-electrode, and method for manufacturing a bio-electrode

ABSTRACT

The present invention provides a bio-electrode composition including: a resin containing a main chain having a urethane bond and two side chains each having a silicon-containing group; and an electro-conductive material, wherein the electro-conductive material is a polymer compound having one or more repeating units selected from fluorosulfonic acid salts shown by the following formulae (1)-1 and (1)-2, sulfonimide salts shown by the following formula (1)-3, and sulfonamide salts shown by the following formula (1)-4. This can form a living body contact layer for a bio-electrode that is excellent in electric conductivity and biocompatibility, light in weight, manufacturable at low cost, and free from large lowering of the electric conductivity even when it is wetted with water or dried. The present invention also provides a bio-electrode in which the living body contact layer is formed from the bio-electrode composition, and a method for manufacturing the bio-electrode.

TECHNICAL FIELD

The present invention relates to a bio-electrode, which is in contactwith living skin and can detect physical conditions such as a heart rateon the basis of electric signals from the skin, and a method formanufacturing the same, as well as a bio-electrode composition that isusable for a bio-electrode suitably.

BACKGROUND ART

In recent years, wearable devices have been developed progressively withthe spread of Internet of Things (IoT). Representative examples thereofinclude a watch and glasses that can be connected with internet.Wearable devices that can always monitor physical conditions are alsonecessary in a medical field and a sports field, and are expected to bea growth field in the future.

In the medical field, wearable devices have been investigated to monitororganic conditions such as an electrocardiogram measurement, whichdetects heart beats by concentration change of ions released from skinlinked to the heart beats. The electrocardiogram is measured by fittinga body with electrodes on which electro-conductive paste is applied, andthis measurement is performed only once in a short period of time. Onthe other hand, the aim of development of the foregoing medical wearabledevice is to develop devices that monitor health conditions continuouslyfor several weeks. Accordingly, bio-electrodes used for a medicalwearable device have to keep the electric conductivity unchanged and notto cause skin allergies even when being used for a long time. Inaddition to these, it is desirable that the bio-electrode is light inweight and can be manufactured at low cost.

Medical wearable devices include a type in which the device is attachedto a body and a type in which the device is incorporated into clothes.As the type in which the device is attached to a body, it has beenproposed a bio-electrode using water soluble gel containing water andelectrolyte, which are materials of the foregoing electro-conductivepaste (Patent Literature 1). On the other hand, as the type in which thedevice is incorporated into clothes, it has been proposed a means to usecloth in which an electro-conductive polymer such aspoly-3,4-ethylenedioxythiophene-polystyrenesulfonate (PEDOT-PSS) orsilver paste is incorporated into the fibers for electrodes (PatentLiterature 2).

When using the foregoing water soluble gel containing water andelectrolyte, however, the electric conductivity is lost as the water islost due to drying. On the other hand, some people can cause skinallergies by the use of metal with high ionization tendency such ascopper. The use of an electro-conductive polymer such as PEDOT-PSS alsohas a higher risk of skin allergies due to the strong acidity of theelectro-conductive polymer.

One of the role of bio-electrodes include conversion of concentrationchange of ions released from skin to electric signals. Accordingly, theyhave to have higher ionic conductivity. The bio-electrode ofwater-soluble gel electrolyte has higher ionic conductivity. On theother hand, the use of metal having higher electron conductivity such assilver or gold as a bio-electrode causes inferior electric conductanceand higher resistance between the bio-electrode and skin. It has beeninvestigated to use metal nanowire, carbon black, carbon nanotube, etc.,which have excellent electron conductivity, as an electrode material(Patent Literatures 3, 4, and 5). These bio-electrodes, however, failsto exhibit high performance by the reason described above.

To improve the ionic conductivity of solid-state batteries, it has beeninvestigated to combine ionic electrolyte and polyethylene glycol. Theionic conduction is brought by ions hopping on the polyethylene glycolchain.

It has started to use silicone for use such as medical tubes and so onsince silicone is excellent in biocompatibility and repels water such asperspiration. However, it is difficult to use silicone forbio-electrodes since silicone is an insulating material.

Urethane may be usable for bio-electrodes since urethane is alsoexcellent in biocompatibility, and the electric insulation property isnot so high as that of silicone. Urethane, however, has higherhydrophilicity and is hydrolysable, thereby being unsuitable for usesthat involve contact with skin for a long time.

In order to prevent the hydrolysis of polyurethane, polyurethane havinga silicone main chain has been investigated (Patent Literature 6).

When the bio-electrode is away from skin, it becomes impossible toobtain information from the body. Just the change of contact areafluctuates the quantity of electricity to be conducted, therebyfluctuating the baseline of an electrocardiogram (electric signals).Accordingly, the bio-electrode have to be in contact with skincontinually without changing the contact area in order to obtain stableelectric signals from a body. For that purpose, the bio-electrodepreferably has tackiness. It also needs stretchability and flexibilityto cope with expansion and contraction as well as change of bending ofskin.

Urethane is processible to a soft gel state after curing.Water-containing bio-electrodes based on urethane gel have been proposedfor the bio-electrode use described above (Patent Literature 7).

CITATION LIST Patent Literature

-   Patent Literature 1: International Patent Laid-Open Publication No.    WO 2013/039151-   Patent Literature 2: Japanese Unexamined Patent Application    Publication No. 2015-100673-   Patent Literature 3: Japanese Unexamined Patent Application    Publication No. H5-095924-   Patent Literature 4: Japanese Unexamined Patent Application    Publication No. 2003-225217-   Patent Literature 5: Japanese Unexamined Patent Application    Publication No. 2015-019806-   Patent Literature 6: Japanese Unexamined Patent Application    Publication No. 2005-320418-   Patent Literature 7: Japanese Unexamined Patent Application    Publication No. 2011-201955

SUMMARY OF THE INVENTION Technical Problem

The present invention has been accomplished to solve the foregoingproblems, and an object thereof is to provide a bio-electrodecomposition capable of forming a living body contact layer for abio-electrode that is excellent in electric conductivity andbiocompatibility, light in weight, manufacturable at low cost, and freefrom large lowering of the electric conductivity even when it is wettedwith water or dried; a bio-electrode in which the living body contactlayer is formed from the bio-electrode composition; and a method formanufacturing the bio-electrode.

Solution to Problem

To solve the above problems, the present invention provides abio-electrode composition comprising:

a resin containing a main chain having a urethane bond and two sidechains each having a silicon-containing group; and

an electro-conductive material,

wherein the electro-conductive material is a polymer compound having oneor more repeating units selected from the group consisting offluorosulfonic acid salts shown by the following formulae (1)-1 and(1)-2, sulfonimide salts shown by the following formula (1)-3, andsulfonamide salts shown by the following formula (1)-4,

wherein Rf₁ and Rf₂ each represent a hydrogen atom, a fluorine atom, atrifluoromethyl group, or an oxygen atom, provided that when Rf₁represents an oxygen atom, Rf₂ also represents an oxygen atom to form acarbonyl group together with a carbon atom bonded therewith; Rf₃ and Rf₄each represent a hydrogen atom, a fluorine atom, or a trifluoromethylgroup; provided that one or more fluorine atoms are contained in Rf₁ toRf₄; Rf₅, Rf₆, and Rf₇ each represent a fluorine atom, or a linear orbranched alkyl group having 1 to 4 carbon atoms, provided that one ormore fluorine atoms are contained; X⁺ represents a sodium ion, apotassium ion, or a cation having an ammonium ion structure shown by thefollowing formula (1)-5; and “m” is an integer of 1 to 4,

wherein R¹ to R⁴ each represent a hydrogen atom, a linear, branched, orcyclic alkyl group having 1 to 20 carbon atoms, an alkenyl group having2 to 14 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms,optionally having an ether group, an ester group, a carbonyl group, asulfonyl group, a cyano group, an amino group, a nitro group, hydroxygroup, a sulfur atom except in the sulfonyl group, or a halogen atom,and optionally bonded to each other to form a ring.

The inventive bio-electrode composition is capable of forming a livingbody contact layer for a bio-electrode that is excellent in electricconductivity and biocompatibility, light in weight, manufacturable atlow cost, and free from large lowering of the electric conductivity evenwhen it is wetted with water or dried.

It is preferable that the one or more repeating units selected from thegroup consisting of fluorosulfonic acid salts shown by the formulae(1)-1 and (1)-2, sulfonimide salts shown by the formula (1)-3, andsulfonamide salts shown by the formula (1)-4 be one or more repeatingunits selected from repeating units a1 to a7 shown by the followingformulae (2),

wherein R⁵, R⁷, R⁹, R¹², R¹⁴, R¹⁵, and R¹⁷ each independently representa hydrogen atom or a methyl group; R⁶, R⁸, R¹⁰, R¹³, and R¹⁶ eachindependently represent any of a single bond, an ester group, or alinear, branched, or cyclic hydrocarbon group having 1 to 13 carbonatoms optionally having either or both of an ether group and an estergroup; R¹¹ represents a linear or branched alkylene group having 1 to 4carbon atoms, and one or two of the hydrogen atoms in R^(1′) areoptionally substituted with a fluorine atom; Z₁, Z₂, Z₃, Z₄, and Z₆ eachindependently represent any of a single bond, a phenylene group, anaphthylene group, an ether group, an ester group, or an amide group; Z₅represents any of a single bond, an ether group, or an ester group; Z₇represents a single bond, an arylene group having 6 to 12 carbon atoms,or —C(═O)—O—Z⁸—; and Z⁸ represents a linear, branched, or cyclicalkylene group having 1 to 12 carbon atoms, or a divalent aromatichydrocarbon group having 6 to 10 carbon atoms, optionally having anether group, a carbonyl group, or an ester group in Z⁸; Y represents anoxygen atom or an —NR¹⁸— group; R¹⁸ represents a hydrogen atom, or alinear or branched alkyl group having 1 to 4 carbon atoms, optionallybonded to R⁸ to form a ring; “m” is an integer of 1 to 4; a1, a2, a3,a4, a5, a6, and a7 satisfy 0≤a1≤1.0, 0≤a2≤1.0, 0≤a3≤1.0, 0≤a4≤1.0,0≤a5≤1.0, 0≤a6≤1.0, 0≤a7≤1.0, and 0≤a1+a2+a3+a4+a5+a6+a7≤1.0; and Rf₅,Rf₆, Rf₇, and X⁺ have the same meanings as defined above.

With the bio-electrode composition using an electro-conductive materialthat has the repeating unit like this, the effect of the presentinvention can be more improved.

The electro-conductive material is preferably a polymer compound havinga repeating unit of a sulfonamide salt shown by the formula (1)-4.

The bio-electrode composition using an electro-conductive material thathas the repeating unit like this is favorably used for a bio-electrodewith lower irritant to skin.

It is preferable that the resin containing a main chain having aurethane bond and two side chains each having a silicon-containing grouphas a structure shown by the following formula (3),

wherein R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ each represent a linear,branched, or cyclic alkyl group having 1 to 6 carbon atoms, a phenylgroup, a 3,3,3-trifluoropropyl group, or a group shown by—(OSiR²⁵R²⁶)_(n)—OSiR²⁷R²⁸R²⁹; R²⁵, R²⁶, R²⁷, R²⁸, and R²⁹ have the samemeanings as R¹⁹ to R²⁴; “n” is a number in a range of 0 to 100; “A”represents a linear or branched alkylene group having 1 to 4 carbonatoms; and X represents a methylene group or an ether group.

The bio-electrode composition that contains a resin containing a mainchain having a urethane bond and two side chains each having asilicon-containing group like this is favorably used for a bio-electrodewith really excellent repellency.

It is preferable that the resin containing a main chain having aurethane bond and two side chains each having a silicon-containing grouphas a structure containing a polyether main chain shown by the followingformula (4),

wherein R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ each represent a linear,branched, or cyclic alkyl group having 1 to 6 carbon atoms, a phenylgroup, a 3,3,3-trifluoropropyl group, or a group shown by—(OSiR²⁵R²⁶)_(n)—OSiR²⁷R²⁸R²⁹; R²⁵, R²⁶, R²⁷, R²⁸, and R²⁹ have the samemeanings as R¹⁹ to R²⁴; “n” is a number in a range of 0 to 100; “A”represents a linear or branched alkylene group having 1 to 4 carbonatoms; X represents a methylene group or an ether group; R³⁰ represent alinear, branched, or cyclic alkylene group having 2 to 12 carbon atoms;and “v” and “w” satisfy 0<v<1.0, 0<w<1.0, and 0<v+w≤1.0.

The bio-electrode composition that contains a resin containing a mainchain having a urethane bond and two side chains each having asilicon-containing group like this is favorably used for a bio-electrodethat is more flexible and excellent in ionic conductivity.

It is preferable that the resin containing a main chain having aurethane bond and two side chains each having a silicon-containing groupis a reaction product of a diol compound shown by the following formula(5), a polyether compound having a hydroxy group at the terminal, and acompound having an isocyanate group,

wherein R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ each represent a linear,branched, or cyclic alkyl group having 1 to 6 carbon atoms, a phenylgroup, a 3,3,3-trifluoropropyl group, or a group shown by—(OSiR²⁵R²⁵)_(n)—OSiR²⁷R²⁸R²⁹; R²⁵, R²⁶, R²⁷, R²⁸, and R²⁵ have the samemeanings as R¹⁹ to R²⁴; “n” is a number in a range of 0 to 100; “A”represents a linear or branched alkylene group having 1 to 4 carbonatoms; and X represents a methylene group or an ether group.

The bio-electrode composition that contains a resin containing a mainchain having a urethane bond and two side chains each having asilicon-containing group like this facilitates to form a living bodycontact layer for a bio-electrode that is excellent in electricconductivity and biocompatibility, light in weight, manufacturable atlow cost, and free from large lowering of the electric conductivity evenwhen it is wetted with water or dried.

It is preferable that the bio-electrode composition further comprises anorganic solvent.

This further improve the coating properties of the bio-electrodecomposition.

It is preferable that the bio-electrode composition further comprises acarbon material.

The bio-electrode composition like this is capable of forming a livingbody contact layer with more improved electric conductivity.

It is preferable that the carbon material be either or both of carbonblack and carbon nanotube.

In the bio-electrode composition of the present invention, it ispossible to use these carbon materials particularly favorably.

The present invention also provides a bio-electrode comprising anelectro-conductive base material and a living body contact layer formedon the electro-conductive base material;

wherein the living body contact layer is a cured material of thebio-electrode composition described above.

The inventive bio-electrode is excellent in electric conductivity andbiocompatibility, light in weight, manufacturable at low cost, and freefrom large lowering of the electric conductivity even when it is wettedwith water or dried.

It is preferable that the electro-conductive base material comprises oneor more species selected from gold, silver, silver chloride, platinum,aluminum, magnesium, tin, tungsten, iron, copper, nickel, stainlesssteel, chromium, titanium, and carbon.

In the bio-electrode of the present invention, it is possible to useelectro-conductive base material like this particularly favorably.

The present invention also provides a method for manufacturing abio-electrode having an electro-conductive base material and a livingbody contact layer formed on the electro-conductive base material,comprising:

applying the bio-electrode composition described above onto theelectro-conductive base material; and curing the bio-electrodecomposition; thereby forming the living body contact layer.

The inventive method for manufacturing a bio-electrode makes it possibleto easily manufacture a bio-electrode that is excellent in electricconductivity and biocompatibility, light in weight, manufacturable atlow cost, and free from large lowering of the electric conductivity evenwhen it is wetted with water or dried.

It is preferable that the electro-conductive base material comprises oneor more species selected from gold, silver, silver chloride, platinum,aluminum, magnesium, tin, tungsten, iron, copper, nickel, stainlesssteel, chromium, titanium, and carbon.

The electro-conductive base material like this is usable for theinventive method for manufacturing a bio-electrode particularlyfavorably.

Advantageous Effects of Invention

As described above, the inventive bio-electrode composition makes itpossible to form a living body contact layer for a bio-electrode that iscapable of conducting electric signals efficiently from skin to a device(i.e., excellent in electric conductivity), free from the risk ofcausing allergies even when it is worn on skin for a long time (i.e.,excellent in biocompatibility), light in weight, manufacturable at lowcost, and free from large lowering of the electric conductivity evenwhen it is wetted with water or dried. The electric conductivity can bemore improved by adding a carbon material. It is possible to manufacturea bio-electrode with high flexibility and stretchability to be always incontact with skin by combining flexible urethane gel. Accordingly, theinventive bio-electrode, with the living body contact layer being formedby using the inventive bio-electrode composition like this, isparticularly suitable as a bio-electrode used for a medical wearabledevice. Moreover, the inventive method for manufacturing a bio-electrodemakes it possible to manufacture such a bio-electrode easily at lowcost.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic sectional view showing an example of the inventivebio-electrode;

FIG. 2 is a schematic sectional view showing an example of the inventivebio-electrode worn on a living body;

FIG. 3(a) is a schematic view of the bio-electrode produced in Examplesof the present invention viewed from the living body contact layer side;and FIG. 3(b) is a schematic view of the bio-electrode produced inExamples of the present invention viewed from the electro-conductivebase material side; and

FIG. 4 is a photograph of a scene of measuring impedance on the surfaceof skin by using the bio-electrode produced in Examples of the presentinvention.

DESCRIPTION OF EMBODIMENTS

As described above, it has been desired to develop a bio-electrodecomposition capable of forming a living body contact layer for abio-electrode that is excellent in electric conductivity andbiocompatibility, light in weight, manufacturable at low cost, and freefrom large lowering of the electric conductivity even when it is wettedwith water or dried; a bio-electrode in which the living body contactlayer is formed from the bio-electrode composition; and a method formanufacturing the same.

The bio-electrode has a function to convert concentration change of ionsreleased from skin to electric signals. Accordingly, it is necessary toincrease the ionic conductivity in the film. Metal films have very highelectron conductivity, but have lower performance as a bio-electrode.This is due to lower ionic conductivity of metal films. Water or polarsolvent that contains ions has higher ionic conductivity, andbio-electrodes of water-soluble gel that contain hydrated water-solublepolymers and ions have been used widely. However, it has a drawback oflowering the ionic conductivity when the water is dried as describedabove. It has been required for a dry bio-electrode with high ionicconductivity without containing water or organic solvent.

The method for improving the ionic conductivity other than the additionof a salt of ionic electrolyte include combination of polyether orpolycarbonate and a salt. The ions move on the oxygen functional groupsof these polymers such that they are hopping. In comparison betweenpolyether and polycarbonate, polyether has stretchability, butpolycarbonate does not have stretchability. Since the bio-electrodeadhered on skin have to stretch along with the expansion and contractionof skin, polyether is more preferable.

The bio-electrode film composed of a bio-electrode composition isrequired to be always in contact with skin without fluctuating the area.Fluctuation of contact area is not preferable since it changes theelectric conductivity. Accordingly, the bio-electrode film has to be asoft film. As long as it is a soft film, the tackiness is inessential. Asoft bio-electrode in a gel state can be always in contact with skin togive stable biological signals. Polyurethane in which a polyether groupis introduced is excellent in flexibility. In this case, the urethaneresin is formed by the reaction of an isocyanate compound and polyetherhaving hydroxy groups at the terminals. A soft urethane resin withtackiness in a gel state can be produced by reducing the crosslinkingdensity.

Illustrative examples of the salt of ionic electrolyte include ionicliquid. Ionic liquids are characterized by high thermal and chemicalstability as well as excellent electric conductivity, thereby havingbeen widely used for battery uses. Illustrative examples of known ionicliquid include hydrochloric acid salt, hydrobromic acid salt, hydroiodicacid salt, trifluoromethanesulfonic acid salt, nonafluorobutanesulfonicacid salt, bis(trifluoromethanesulfonyl)imidic acid salt,hexafluorophosphate salt, and tetrafluoroborate salt of sulfonium,phosphonium, ammonium, morpholinium, pyridinium, pyrrolidinium, andimidazolium. However, these salts (particularly, the ones with lowmolecular weight) are generally liable to hydrate, thereby causing abio-electrode to lower the electric conductivity due to extraction ofthe salt with perspiration or by washing when these salts are added to aself-adhesive composition to form the living body contact layer. Thetetrafluoroborate salt is highly toxic, and the other salts have highsolubility in water to easily permeate into skin, each of which causesrough dry skin (i.e., highly irritative to skin).

Additionally, urethane resins have higher hydrophilicity and aredegraded by gradual hydrolysis of the urethane bonds. To decrease thehydrolysis, it is efficient to increase the hydrophobicity. Accordingly,silicone-urethanes having a silicone bond have been investigated. Aurethane resin in which silicone is introduced into the main chain hasboth of a silicone moiety and a urethane moiety in the main chain. Inthis case, introduction of silicone lowers the stretchability and thestrength. This is because silicone has lower strength compared tourethane. When silicone with shorter chain length is introduced into theside chain, the strength is rather improved far from being lowered. Thisis probably due to increased hydrogen bonding of the urethane bondcaused by introduction of a silicone side chain with shorter chainlength. The silicone side chain is capable of increasing the repellencymore efficiently.

For highly-sensitive bio-electrodes, which can detect weak biologicalsignals, higher ionic conductivity is necessary. Silicones areinsulators, but urethanes are allowed to have improved ionicconductivity by introducing polyether into the chain extending moiety.From this viewpoint, urethanes that have polyethers introduced into themain chain are preferable rather than urethanes that have polysiloxanesintroduced into the main chain. Among the polyethers, polyethyleneglycol chains have highest electric conductivity and are preferable.

Accordingly, the inventors have diligently investigated the aboveproblems to find that bio-electrode compositions that contain a resincontaining a main chain having a urethane bond and two side chains eachhaving a silicon-containing group excels in repellency and electricconductivity, and to find that bio-electrode compositions with theelectro-conductive material being a polymeric salt do not cause loweringof electric conductivity due to water extraction or irritating the skindue to passing through skin; thereby bringing the present invention tocompletion.

That is, the present invention is a bio-electrode compositioncomprising:

a resin containing a main chain having a urethane bond and two sidechains each having a silicon-containing group; and

an electro-conductive material,

wherein the electro-conductive material is a polymer compound having oneor more repeating units selected from the group consisting offluorosulfonic acid salts shown by the following formulae (1)-1 and(1)-2, sulfonimide salts shown by the following formula (1)-3, andsulfonamide salts shown by the following formula (1)-4,

wherein Rf₁ and Rf₂ each represent a hydrogen atom, a fluorine atom, atrifluoromethyl group, or an oxygen atom, provided that when Rf₁represents an oxygen atom, Rf₂ also represents an oxygen atom to form acarbonyl group together with a carbon atom bonded therewith; Rf₃ and Rf₄each represent a hydrogen atom, a fluorine atom, or a trifluoromethylgroup; provided that one or more fluorine atoms are contained in Rf₁ toRf₄; Rf₅, Rf₆, and Rf₇ each represent a fluorine atom, or a linear orbranched alkyl group having 1 to 4 carbon atoms, provided that one ormore fluorine atoms are contained; X⁺ represents a sodium ion, apotassium ion, or a cation having an ammonium ion structure shown by thefollowing formula (1)-5; and “m” is an integer of 1 to 4,

wherein R¹ to R⁴ each represent a hydrogen atom, a linear, branched, orcyclic alkyl group having 1 to 20 carbon atoms, an alkenyl group having2 to 14 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms,optionally having an ether group, an ester group, a carbonyl group, asulfonyl group, a cyano group, an amino group, a nitro group, hydroxygroup, a sulfur atom except in the sulfonyl group, or a halogen atom,and optionally bonded to each other to form a ring.

Hereinafter, the present invention will be described specifically, butthe present invention is not limited thereto.

<Bio-Electrode Composition>

The inventive bio-electrode composition contains an electro-conductivematerial (polymeric ionic material) and a resin containing a main chainhaving a urethane bond and two side chains each having asilicon-containing group (urethane resin having two pendantsilicon-containing group in the side chains branched from a carbon atomof the main chain). Hereinafter, each component will be described morespecifically.

[Electro-Conductive Material (Salt)]

The salt to be added to the inventive bio-electrode composition as anelectro-conductive material is a polymer compound having one or morerepeating units selected from the group consisting of fluorosulfonicacid salts shown by any of the following formulae (1)-1 and (1)-2,sulfonimide salts shown by the following formula (1)-3, and sulfonamidesalts shown by the following formula (1)-4,

wherein Rf₁ and Rf₂ each represent a hydrogen atom, a fluorine atom, atrifluoromethyl group, or an oxygen atom, provided that when Rf₁represents an oxygen atom, Pf₂ also represents an oxygen atom to form acarbonyl group together with a carbon atom bonded therewith; Rf₃ and Rf₄each represent a hydrogen atom, a fluorine atom, or a trifluoromethylgroup; provided that one or more fluorine atoms are contained in Rf₁ toRf₄; Rf₅, Rf₆, and Rf₇ each represent a fluorine atom, or a linear orbranched alkyl group having 1 to 4 carbon atoms, provided that one ormore fluorine atoms are contained; X⁺ represents a sodium ion, apotassium ion, or a cation having an ammonium ion structure shown by thefollowing formula (1)-5; and “m” is an integer of 1 to 4,

wherein R¹ to R⁴ each represent a hydrogen atom, a linear, branched, orcyclic alkyl group having 1 to 20 carbon atoms, an alkenyl group having2 to 14 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms,optionally having an ether group, an ester group, a carbonyl group, asulfonyl group, a cyano group, an amino group, a nitro group, hydroxygroup, a sulfur atom except in the sulfonyl group, or a halogen atom,and optionally bonded to each other to form a ring.

The electro-conductive material used for the inventive bio-electrodecomposition, being the salt as described above, is excellent in electricconductivity, and being a polymeric salt (ionic polymer), has extremelylow water solubility and does not pass through skin.

The irritation to skin is higher as the polymeric acid is strongerbefore neutralization with sodium, potassium, ammonium, etc. Among theelectro-conductive materials described above, the sulfonamide shown bythe formula (1)-4 has lowest acidity and lowest irritation to skinthereby, and is preferably used.

It is preferable that the one or more repeating units selected from thegroup consisting of fluorosulfonic acid salts shown by the formulae(1)-1 and (1)-2, sulfonimide salts shown by the formula (1)-3, andsulfonamide salts shown by the formula (1)-4 be one or more repeatingunits selected from repeating units a1 to a7 shown by the followingformulae (2),

wherein R⁵, R⁷, R⁹, R¹², R¹⁴, R¹⁵, and R¹⁷ each independently representa hydrogen atom or a methyl group; R⁶, R⁸, R¹⁰, R¹³, and R¹⁶ eachindependently represent any of a single bond, an ester group, or alinear, branched, or cyclic hydrocarbon group having 1 to 13 carbonatoms optionally having either or both of an ether group and an estergroup; R¹¹ represents a linear or branched alkylene group having 1 to 4carbon atoms, and one or two of the hydrogen atoms in R¹¹ are optionallysubstituted with a fluorine atom; Z₁, Z₂, Z₃, Z₄, and Z₅ eachindependently represent any of a single bond, a phenylene group, anaphthylene group, an ether group, an ester group, or an amide group; Z₅represents any of a single bond, an ether group, or an ester group; Z₇represents a single bond, an arylene group having 6 to 12 carbon atoms,or —C(═O)—O—Z⁸—; and Z⁸ represents a linear, branched, or cyclicalkylene group having 1 to 12 carbon atoms, or a divalent aromatichydrocarbon group having 6 to 10 carbon atoms, optionally having anether group, a carbonyl group, or an ester group in Z⁸; Y represents anoxygen atom or an —NR¹⁸— group; R¹⁸ represents a hydrogen atom, or alinear or branched alkyl group having 1 to 4 carbon atoms, optionallybonded to R⁸ to form a ring; “m” is an integer of 1 to 4; a1, a2, a3,a4, a5, a6, and a7 satisfy 0≤a1≤1.0, 0≤a2≤1.0, 0≤a3≤1.0, 0≤a4≤1.0,0≤a5≤1.0, 0≤a6≤1.0, 0≤a7≤1.0, and 0≤a1+a2+a3+a4+a5+a6+a7≤1.0; and Rf₅,Rf₆, Rf₇, and X⁺ have the same meanings as defined above.

The fluorosulfonic acid salt monomer to obtain the repeating unit a1 inthe formulae (2) is not particularly limited, and illustrative examplesthereof include the following.

In the formulae, R⁵ and X have the same meanings as defined above.

The fluorosulfonic acid salt monomer to obtain the repeating unit a2 inthe formulae (2) is not particularly limited, and illustrative examplesthereof include the following.

In the formulae, R⁹ and X have the same meanings as defined above.

The fluorosulfonic acid salt monomer to obtain the repeating unit a4 inthe formulae (2) is not particularly limited, and illustrative examplesthereof include the following.

In the formulae, R¹² and X have the same meanings as defined above.

The fluorosulfonic acid salt monomer to obtain the repeating unit a5 inthe formulae (2) is not particularly limited, and illustrative examplesthereof include the following.

In the formulae, R¹⁴ and X have the same meanings as defined above.

The sulfonimide salt monomer to obtain the repeating unit a6 in theformulae (2) is not particularly limited, and illustrative examplesthereof include the following.

In the formulae, R¹⁵ and X have the same meanings as defined above.

The sulfonamide salt monomer to obtain the repeating unit a7 in theformulae (2) is not particularly limited, and illustrative examplesthereof include the following.

In the formulae, R¹⁷ and X have the same meanings as defined above.

The ammonium cation structure shown by the formula (1)-5 is notparticularly limited, and illustrative examples thereof include thefollowing.

The bio-electrode composition used for the present invention preferablycontains an ionic polymer that has a repeating unit (s) of an ionicmonomer shown by a1 to a7, but the ionic polymer may also becopolymerized with repeating unit-b having tackiness function. Themonomer for obtaining the repeating unit-b that brings tackiness is notparticularly limited, and concrete examples thereof include thefollowing.

In the formulae, R represents a hydrogen atom or a methyl group.

To improve the repellency, it is also possible to copolymerize repeatingunit-c, which contains a silicon. The monomer for obtaining therepeating unit-c containing a silicon is not particularly limited, andconcrete examples thereof include the following.

In the formulae, “n” is an integer of 0 to 100.

Additionally, it is also possible to copolymerize repeating unit-d,which has a glyme chain, to improve the electric conductivity. Themonomer for obtaining the repeating unit-d having a glyme chain is notparticularly limited, and concrete examples thereof include thefollowing.

In the formulae, R represents a hydrogen atom or a methyl group.

By bonding an electro-conductive material to be added to the inventivebio-electrode composition and a urethane resin to be the base of thebio-electrode, which will be described later, the electro-conductivematerial and the urethane resin are integrated, thereby making itpossible to prevent elution of the electro-conductive material. Theelectro-conductive material and the urethane resin can be bonded by themethod of copolymerizing repeating unit-e, which has a hydroxy group, anoxirane group, an oxetane group, or an isocyanate group, in the urethanepolymer to form the urethane resin in the presence of theelectro-conductive material. The monomer for obtaining the repeatingunit-e having a hydroxy group, an oxirane group, an oxetane group, or anisocyanate group is not particularly limited, and concrete examplesthereof include the following.

In the formulae, R represents a hydrogen atom or a methyl group.

As the method for synthesizing these polymer compounds to produce theelectro-conductive material, heat polymerization can be performed, forexample, on a desired monomer that contains one or more repeating unitsa1 to a7 among the monomers to give the repeating unit a1, a2, a3, a4,a5, a6, a7, “b”, “c”, “d”, or “e” by adding a radical polymerizationinitiator in an organic solvent to give an electro-conductive materialas a polymer compound of copolymer.

As the organic solvent used in the polymerization, toluene, benzene,tetrahydrofuran, diethyl ether, dioxane and so on can be exemplified.Illustrative examples of the polymerization initiator include2,2′-azobis(isobutyronitrile) (AIBN),2,2′-azobis(2,4-dimethylvaleronitrile), dimethyl2,2′-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide.

The temperature in the heat polymerization is preferably 50 to 80° C.The reaction time is preferably 2 to 100 hours, more preferably 5 to 20hours.

The ratios of the repeating units a1 to a7, “b”, “c”, “d”, and “e” arepreferably 0≤a1≤1.0, 0≤a2≤1.0, 0≤a3≤1.0, 0≤a4≤1.0, 0≤a5≤1.0, 0≤a6≤1.0,0≤a7≤1.0, 0≤a1+a2+a3+a4+a5+a6+a7≤1.0, 0≤b≤1.0, 0≤c≤1.0, 0≤d≤1.0, and0≤e≤1.0; more preferably 0≤a1≤0.9, 0≤a2≤0.9, 0≤a3≤0.9, 0≤a4≤0.9,0≤a5≤0.9, 0≤a6≤0.9, 0≤a7≤0.9, 0.1≤a1+a2+a3+a4+a5+a6+a7≤0.9, 0≤b≤0.9,0≤c≤0.9, 0≤d≤0.8, and 0≤e≤0.5; and further preferably 0≤a1≤0.8,0≤a2≤0.8, 0≤a3≤0.8, 0≤a4≤0.8, 0≤a5≤0.8, 0≤a6≤0.8, 0≤a7≤0.8,0.2≤a1+a2+a3+a4+a5+a6+a7≤0.8, 0≤b≤0.8, 0≤c≤0.8, 0≤d≤0.7, and 0≤e≤0.5.

Incidentally, a1+a2+a3+a4+a5+a6+a7+b+c+d+e=1, for example, means thatthe total amount of repeating units a1 to a7, “b”, “c”, “d”, and “e” is100 mol % on the basis of the total amount of the whole repeating unitsin a polymer compound that contains repeating units-a1 to a7, “b”, “c”,“d”, and “e”; and a1+a2+a3+a4+a5+a6+a7+b+c+d+e<1 means that the totalamount of repeating units-a1 to a7, “b”, “c”, “d”, and “e” is less than100 mol % on the basis of the total amount of the whole repeating units,and another repeating unit(s) is contained other than the repeatingunits a1 to a7, “b”, “c”, “d”, and “e”.

The molecular weight of the polymer, as a weight average molecularweight, is preferably 500 or more, more preferably in a range of 1000 ormore and 1000000 or less, further preferably in a range of 2000 or moreand 500000 or less. The presence of a large amount of residual monomer,which is not incorporated into the polymer after polymerization of ionicmonomers, can permeate to skin in a biocompatibility test to causeallergy. Accordingly, the amount of residual monomer have to bedecreased. The amount of residual monomer is preferably 10 parts by massor less when the total polymer is 100 parts by mass.

The amount of the ionic polymer blended as an electro-conductivematerial is preferably in a range of 0.1 to 300 parts by mass, morepreferably 1 to 200 parts by mass on the basis of 100 parts by mass ofthe urethane resin. The ionic polymer blended as an electro-conductivematerial may be used singly or in admixture of two or more kinds.

As a method for synthesizing the salt shown by a1 to a7 in the formulae(2) when X is a cation having an ammonium structure shown by the formula(1)-5, the method described in JP 2010-113209A can be exemplified, forexample. More specifically, it can be obtained by a method in whichsodium fluorosulfonate containing the fluorosulfonate anion is mixedwith quarternary ammonium chloride containing a cation having one or twoquarternary ammonium cation structure described above in an organicsolvent, for example. In this case, it is preferable to remove sodiumchloride that is formed as a bi-product by washing with water.

[Resin Containing Main Chain Having Urethane Bond and Two Side ChainsEach Having Silicon-Containing Group (Urethane Resin)]

The resin to be blended in the inventive bio-electrode composition is acomponent to hold the electro-conductive material and a conductivityimprover such as carbon to improve the electric conductivity, and haveto be soft as well as flexible and stretchable to be in contact withskin in accordance with the motion, and is required to have tackiness insome cases. As such a material, a resin having a urethane bond in themain chain and a silicon-containing group in each of the two side chainsis used. Among them, a resin based on urethane gel (urethane gelcomposition) is preferably used. In order to exhibit the functions as abio-electrode without being affected by water, repellency is alsonecessary. Accordingly, silicone-urethane gel is preferably used.

The urethane gel composition is exemplified by the one that can beobtained by mixing a hydroxy compound and an isocyanate compound, forexample, and by adding a catalyst to promote the reaction in some cases.The urethane gel with lower hardness can be obtained by reducing thecrosslinking density or totally inhibiting the crosslinking.Accordingly, it is preferable to avoid addition of a cross-linkablehydroxy group-containing compound that has three or more of hydroxygroups in one molecule as possible or to reduce the amount.

The method for forming urethane gel can be exemplified by a one shotmethod of mixing a hydroxy compound, an isocyanate compound, a diolcompound shown by the formula (5), and an ionic polymer, followed bycuring thereof by heating, etc. The one shot method has an advantage ofhigher productivity, but sometimes lowers the strength or stretchabilitydue to remaining of unreacted hydroxy groups or isocyanate groups.

It is also possible to exemplify a prepolymer method in which a hydroxycompound and an isocyanate compound are previously mixed, and then ahydroxy compound, an isocyanate compound, a diol compound shown by theformula (5), and an ionic polymer are additionally mixed, followed bycuring. In this case, the hydroxy groups and the isocyanate groups havesufficiently reacted, and there is a feature of lower ratio of residualisocyanate groups. When the prepolymer is prepared, the diol compoundshown by the formula (5) can also be mixed not only the hydroxy compoundand the isocyanate compound. In case of preparing the prepolymer, it ispreferable that excess isocyanate groups has been mixed to make theterminals of prepolymer be isocyanate.

The urethane resin contained in the inventive bio-electrode compositionpreferably has a urethane bond in the main chain and twosilicon-containing groups in the side chains branched from a carbon atomof the main chain shown by the following formula (3). This makes itpossible to improve the repellency. Although urethane resin in whichsilicone is incorporated into the main chain lowers the strength of thefilm, urethane structure which has pendant silicon-containing groupsentails less lowering of the strength and is usable for a bio-electrodecomposition favorably.

In the formula, R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ each represent alinear, branched, or cyclic alkyl group having 1 to 6 carbon atoms, aphenyl group, a 3,3,3-trifluoropropyl group, or a group shown by—(OSiR²⁵R²⁶)_(n)—OSiR²⁷R²⁸R²⁹; R²⁵, R²⁶, R²⁷, R²⁸, and R²⁹ have the samemeanings as R¹⁹ to R²⁴; “n” is a number in a range of 0 to 100; “A”represents a linear or branched alkylene group having 1 to 4 carbonatoms; and X represents a methylene group or an ether group.

The resin having a urethane bond in the main chain and twosilicon-containing groups in the side chains branched from a carbon atomof the main chain is preferably a resin that has a structure containinga polyether main chain shown by the following formula (4). Thepolyurethane having a polyether main chain makes it possible to form aflexible living body electrode film and to improve the ionicconductivity.

In the formula, R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ each represent alinear, branched, or cyclic alkyl group having 1 to 6 carbon atoms, aphenyl group, a 3,3,3-trifluoropropyl group, or a group shown by—(OSiR²⁵R²⁶)_(n)—OSiR²⁷R²⁸R²⁹; R²⁵, R²⁶, R²⁷, R²⁸, and R²⁹ have the samemeanings as R¹⁹ to R²⁴; “n” is a number in a range of 0 to 100; “A”represents a linear or branched alkylene group having 1 to 4 carbonatoms; X represents a methylene group or an ether group; R³⁰ represent alinear, branched, or cyclic alkylene group having 2 to 12 carbon atoms;and “v” and “w” satisfy 0<v<1.0, 0<w<1.0, and 0<v+w≤1.0.

It is further preferable that the resin having a urethane bond in themain chain and two silicon-containing groups in the side chains branchedfrom a carbon atom of the main chain is a reaction product of a diolcompound shown by the following formula (5), a polyether compound havinga hydroxy group(s) at the terminal, and a compound having an isocyanategroup(s).

In the formula, R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ each represent alinear, branched, or cyclic alkyl group having 1 to 6 carbon atoms, aphenyl group, a 3,3,3-trifluoropropyl group, or a group shown by—(OSiR²⁵R²⁶)_(n)—OSiR²⁷R²⁸R²⁹; R²⁵, R²⁶, R²⁷, R²⁸, and R²⁹ have the samemeanings as R¹⁹ to R²⁴; “n” is a number in a range of 0 to 100; “A”represents a linear or branched alkylene group having 1 to 4 carbonatoms; and X represents a methylene group or an ether group.

The diol compound having pendant silicon-containing groups shown by thefollowing formula (5) can be obtained by reaction of adihydroxydialkenyl compound and a short-chain silicon-containingcompound having a SiH group(s) in the presence of a platinum catalyst,for example.

The diol compound shown by the formula (5) is not particularly limited,and concrete examples thereof include the following.

In the formulae, each number of repeating unit shows the average value.

The diol compound preferably has 1 to 20 silicon atoms in one sidechain. When the number of silicon atoms is in this range, thestretchable film has improved strength. Additionally, the short-chainsilicon-containing group with 1 to 20 silicon atoms is sufficient forimproving the repellency.

In producing the urethane resin contained in the inventive bio-electrodecomposition, it is preferable to add a compound that has plurality ofhydroxy groups (hydroxy compound) in addition to the diol compounddescribed above for extending the chain length or crosslinking. Thehydroxy compound preferably has a polyether structure.

The hydroxy compound is not particularly limited, and concrete examplesthereof include the following.

By mixing a hydroxy compound and an isocyanate compound, urethane bondsare formed to promote the reaction for curing, thereby forming aurethane resin.

The isocyanate compound to be used for the reaction with a hydroxycompound is not particularly limited, and concrete examples thereofinclude the following.

In the formulae, “p” is an integer of 1 or more.

As the isocyanate compound, it is preferable to use a compound having ablocked isocyanate group in which the isocyanate group is protected by asubstituent. This facilitates to control the reaction even when thereactivity with the hydroxy group-containing compound is high. Theisocyanate compound sometimes reacts with moisture in the air during thestorage to cause inactivation of the isocyanate group, and requires fullattention such as fully preventing moisture for the storage. In thecompound having a blocked isocyanate group, however, these phenomena canbe prevented.

The blocked isocyanate group is deprotected by heating to be anisocyanate group. Illustrative examples thereof include isocyanategroups substituted with alcohol, phenol, thioalcohol, imine, ketimine,amine, lactam, pyrazol, oxime, and 3-diketone.

In using a blocked isocyanate compound, a catalyst can be added todecrease the temperature for deprotecting the blocked isocyanate group.This catalyst is not particularly limited, and known examples thereofinclude organic tin compounds such as dibutyl tin dilaurate, bismuthsalts, and zinc carboxylate such as zinc 2-ethylhexanoate and zincacetate.

It is preferable to use zinc α,β-unsaturated carboxylate as a catalystfor dissociation of blocked isocyanate as described in JP 2012-152725A.

In the synthesis of urethane resin contained in the inventivebio-electrode composition, it is also possible to add a compound thathas an amino group(s). Reaction of an isocyanate group and an aminogroup forms a urea bond. The moieties of urethane bond and urea bond arecalled hard segments, and their hydrogen bonds improve the strength. Itis possible to improve the strength by introducing a urea bond(s) inaddition to the urethane bond(s) not only the urethane bond(s) alone.

[Organic Solvent]

The inventive bio-electrode composition may contain organic solvent. Theorganic solvent is not particularly limited, and illustrative examplesthereof include aromatic hydrocarbon solvent such as toluene, xylene,cumene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene,1,3,5-trimethylbenzene, styrene, α-methylstyrene, butylbenzene,sec-butylbenzene, isobutylbenzene, cymene, diethylbenzene,2-ethyl-p-xylene, 2-propyltoluene, 3-propyltoluene, 4-propyltoluene,1,2,3,5-tetramethyltoluene, 1,2,4,5-tetramethyltoluene,tetrahydronaphthalene, 4-phenyl-1-butene, tert-amylbenzene, amylbenzene,2-tert-butyltoluene, 3-tert-butyltoluene, 4-tert-butyltoluene,5-isopropyl-m-xylene, 3-methylethylbenzene, tert-butyl-3-ethylbenzene,4-tert-butyl-o-xylene, 5-tert-butyl-m-xylene, tert-butyl-p-xylene,1,2-diisopropylbenzene, 1,3-diisopropylbenzene, 1,4-diisopropylbenzene,dipropylbenzene, 3,9-dodecadiyne, pentamethylbenzene, hexamethylbenzene,hexylbenzene, and 1,3,5-triethylbenzene; aliphatic hydrocarbon solventsuch as n-heptane, isoheptane, 3-methylhexane, 2,3-dimethylpentane,3-ethylpentane, 1,6-heptadiene, 5-methyl-1-hexyn, norbornane,norbornene, dicyclopentadiene, 1-methyl-1,4-cyclohexadiene, 1-heptyne,2-heptyne, cycloheptane, cycloheptene, 1,3-dimethylcyclopentane,ethylcyclopentane, methylcyclohexane, 1-methyl-1-cyclohexene,3-methyl-1-cyclohexene, methylenecyclohexane, 4-methyl-1-cyclohexene,2-methyl-1-hexene, 2-methyl-2-hexene, 1-heptene, 2-heptene, 3-heptene,n-octane, 2,2-dimethylhexane, 2,3-dimethylhexane, 2,4-dimethylhexane,2,5-dimethylhexane, 3,3-dimethylhexane, 3,4-dimethylhexane,3-ethyl-2-methylpentane, 3-ethyl-3-methylpentane, 2-methylheptane,3-methylheptane, 4-methylheptane, 2,2,3-trimethylpentane,2,2,4-trimethylpentane, cyclooctane, cyclooctene,1,2-dimethylcyclohexane, 1,3-dimethylcyclohexane,1,4-dimethylcyclohexane, ethylcyclohexane, vinylcyclohexane,isopropylcyclopentane, 2,2-dimethyl-3-hexene, 2,4-dimethyl-1-hexene,2,5-dimethyl-1-hexene, 2,5-dimethyl-2-hexene, 3,3-dimethyl-1-hexene,3,4-dimethyl-1-hexene, 4,4-dimethyl-1-hexene, 2-ethyl-1-hexene,2-methyl-1-heptene, 1-octene, 2-octene, 3-octene, 4-octene,1,7-octadiene, 1 octyne, 2-octyne, 3-octyne, 4-octyne, n-nonane,2,3-dimethylheptane, 2,4-dimethylheptane, 2,5-dimethylheptane,3,3-dimethylheptane, 3,4-dimethylheptane, 3,5-dimethylheptane,4-methylheptane, 2-methyloctane, 3-methyloctane, 4-methyloctane,2,2,4,4-tetramethylpentane, 2,2,4-trimethylhexane,2,2,5-trimethylhexane, 2,2-dimethyl-3-heptene, 2,3-dimethyl-3-heptene,2,4-dimethyl-1-heptene, 2,6-dimethyl-1-heptene, 2,6-dimethyl-3-heptene,3,5-dimethyl-3-heptene, 2,4,4-trimethyl-1-hexene,3,5,5-trimethyl-1-hexene, 1-ethyl-2-methylcyclohexane,1-ethyl-3-methylcyclohexane, 1-ethyl-4-methylcyclohexane,propylcyclohexane, isopropylcyclohexane, 1,1,3-trimethylcyclohexane,1,1,4-trimethylcyclohexane, 1,2,3-trimethylcyclohexane,1,2,4-trimethylcyclohexane, 1,3,5-trimethylcyclohexane,allylcyclohexane, hydrindane, 1,8-nonadiene, 1-nonyne, 2-nonyne,3-nonyne, 4-nonyne, 1-nonene, 2-nonene, 3-nonene, 4-nonene, n-decane,3,3-dimethyloctane, 3,5-dimethyloctane, 4,4-dimethyloctane,3-ethyl-3-methylheptane, 2-methylnonane, 3-methylnonane, 4-methylnonane,tert-butylcyclohexane, butylcyclohexane, isobutylcyclohexane,4-isopropyl-1-methylcyclohexane, pentylcyclopentane,1,1,3,5-tetramethylcyclohexane, cyclododecane, l-decene, 2-decene,3-decene, 4-decene, 5-decene, 1,9-decadiene, decahydronaphthalene,1-decyne, 2-decyne, 3-decyne, 4-decyne, 5-decyne, 1,5,9-decatriene,2,6-dimethyl-2,4,6-octatriene, limonene, myrcene,1,2,3,4,5-pentamethylcyclopentadiene, α-phellandrene, pinene, terpinene,tetrahydrodicyclopentadiene, 5,6-dihydrodicyclopentadiene,1,4-decadiyne, 1,5-decadiyne, 1,9-decadiyne, 2,8-decadiyne,4,6-decadiyne, n-undecane, amylcyclohexane, 1-undecene,1,10-undecadiene, 1-undecyne, 3-undecyne, 5-undecyne,tricyclo[6.2.1.0^(2,7)]undeca-4-ene, n-dodecane, 2-methylundecane,3-methylundecane, 4-methylundecane, 5-methylundecane,2,2,4,6,6-pentamethylheptane, 1,3-dimethyladamantane, 1-ethyladamantane,1,5,9-cyclododecatriene, 1,2,4-trivinylcyclohexane, isoparaffin; ketonesolvent such as cyclohexanone, cyclopentanone, 2-octanone, 2-nonanone,2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone,diisobutyl ketone, methylcyclohexanone, and methyl n-pentyl ketone;alcohol solvent such as 3-methoxybutanol, 3-methyl-3-methoxybut and,1-methoxy-2-propanol, and 1-ethoxy-2-propanol; ether solvent such aspropylene glycol monomethyl ether, ethylene glycol monomethyl ether,propylene glycol monoethyl ether, ethylene glycol monoethyl ether,propylene glycol dimethyl ether, diethylene glycol dimethyl ether,diisopropyl ether, diisobutyl ether, diisopentyl ether, di-n-pentylether, methyl cylopentyl ether, methyl cyclohexyl ether, di-n-butylether, di-sec-butyl ether, di-sec-pentyl ether, di-tert-amyl ether,di-n-hexyl ether, and anisole; ester solvent such as propylene glycolmonomethyl ether acetate, propylene glycol monoethyl ether acetate,ethyl lactate, ethyl pyruvate, butyl acetate, methyl3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate,tert-butyl propionate, propylene glycol mono-tert-butyl ether acetate;lactone solvent such as γ-butyrolactone.

The amount of organic solvent is preferably in a range of 10 to 50,000parts by mass on the basis of 100 parts by mass of the resin.

[Carbon Material]

The inventive bio-electrode composition can contain a carbon material asan electric conductivity improver to further enhance the electricconductivity. The carbon material may be exemplified by carbon black andcarbon nanotube, and is preferably either or both of them. The carbonnanotube may be either single layer or multilayer, and the surface maybe modified with an organic group(s). The amount of carbon material ispreferably in a range of 1 to 50 parts by mass on the basis of 100 partsby mass of the resin.

[Electric Conductivity Improver Other than Carbon Material]

The inventive bio-electrode composition also can contain an electricconductivity improver other than the carbon material. Illustrativeexamples thereof include particles of resin coated with noble metal suchas gold, silver, and platinum; nanoparticles of gold, silver, andplatinum; particles of metal oxide such as indium-tin oxide (ITO),indium-zinc oxide (IZO), tin oxide, and zinc oxide; as well as silvernanowire.

As described above, the inventive bio-electrode composition makes itpossible to form a living body contact layer for a bio-electrode that iscapable of conducting electric signals efficiently from skin to a device(i.e., excellent in electric conductivity), free from the risk ofcausing allergies even when it is worn on skin for a long time (i.e.,excellent in biocompatibility), light in weight, manufacturable at lowcost, and free from large lowering of the electric conductivity evenwhen it is wetted with water or dried. It is possible to improve theelectric conductivity still more by adding a carbon material, and tomanufacture a particularly soft bio-electrode with high stretchabilityby combining urethane resin with flexibility and stretchability.Furthermore, it is possible to improve the stretchability and tackinessto skin by additives, and to control the stretchability and tackiness byadjusting the composition of the urethane resin and the thickness of theliving body contact layer appropriately.

<Bio-Electrode>

The present invention also provides a bio-electrode comprising anelectro-conductive base material and a living body contact layer formedon the electro-conductive base material; wherein the living body contactlayer is a cured material of the inventive bio-electrode compositiondescribed above.

Hereinafter, the inventive bio-electrode will be specifically describedby reference to the FIGS., but the present invention is not limitedthereto.

FIG. 1 is a schematic sectional view showing an example of the inventivebio-electrode. The bio-electrode 1 of FIG. 1 has the electro-conductivebase material 2 and the living body contact layer 3 formed on theelectro-conductive base material 2. The living body contact layer 3 is alayer in which the electro-conductive material 4 and the carbon material5 are dispersed in the urethane resin 6. Provided that, the carbonmaterial 5 is an optional component.

When using the bio-electrode 1 of FIG. 1 like this, electric signals arepicked from the living body 7 through the electro-conductive material 4and the carbon material 5 while bringing the living body contact layer 3(i.e., the layer in which the electro-conductive material 4 and thecarbon material 5 are dispersed in the urethane resin 6) into contactwith the living body 7, and then conducted to a sensor device (notshown) through the electro-conductive base material 2 as shown in FIG.2. As described above, the inventive bio-electrode is capable of copingwith both electric conductivity and biocompatibility by using theelectro-conductive material described above, improving the electricconductivity further by adding electric conductivity improver such as acarbon material in accordance with needs, and obtaining electric signalsfrom skin stably in high sensitivity because the contact area with skinis kept constant due to the tackiness thereof.

Hereinafter, each component composing the inventive bio-electrode willbe more specifically described.

[Electro-Conductive Base Material]

The inventive bio-electrode comprises an electro-conductive basematerial. This electro-conductive base material is usually connectedelectrically with a sensor device and so on, and conduct electricalsignals picked from a living body through the living body contact layerto the sensor device and so on.

As the electro-conductive base material, any electro-conductive materialcan be used without being limited to particular ones. However, it ispreferable to comprise one or more species selected from gold, silver,silver chloride, platinum, aluminum, magnesium, tin, tungsten, iron,copper, nickel, stainless steel, chromium, titanium, and carbon, forexample.

The electro-conductive base material may be a hard electro-conductivesubstrate, an electro-conductive film having flexibility, a cloth withthe surface being coated with electro-conductive paste, and a cloth intowhich electro-conductive polymer is kneaded without being limited toparticular substrates. The electro-conductive substrate may be flat,uneven, or mesh-form of woven metal wires, which can be appropriatelyselected in accordance with the use of the bio-electrode.

[Living Body Contact Layer]

The inventive bio-electrode comprises a living body contact layer formedon the electro-conductive base material. This living body contact layeris a part to be actually in contact with a living body when using thebio-electrode, and is a urethane resin that has electric conductivityand repellency. The living body contact layer is a cured material of theinventive bio-electrode composition described above, that is to say, aresin layer that contains the resin and the electro-conductive material(salt) described above, together with additives such as a carbonmaterial in accordance with needs, with the resin containing a mainchain having a urethane bond and two side chains each having asilicon-containing group.

The living body contact layer of the bio-electrode preferably has athickness of 1 μm or more and 5 mm or less, more preferably 2 μm or moreand 3 mm or less. As the living body contact layer is thinner, thetackiness lowers, but the flexibility is improved, and the weightdecreases to improve the compatibility with skin. The thickness of theliving body contact layer can be selected based on the balance offlexibility, tackiness, and texture.

The inventive bio-electrode may be provided with a tacky film separatelyon the living body contact layer as previous bio-electrodes (e.g., thebio-electrode described in JP 2004-033468A) in order to prevent peelingoff of the bio-electrode from a living body during the use. When thetacky film is prepared separately, the tacky film may be formed by usinga raw material for the tacky film such as an acrylic type, a urethanetype, and a silicone type. Particularly, the silicone type is suitablebecause of the high transparency of oxygen, which enables breathingthrough the skin while pasting the same, the high water repellency,which decreases lowering of tackiness due to perspiration, and the lowirritation to skin. It is to be noted that the inventive bio-electrodedoes not necessarily require the tacky film that is prepared separatelydescribed above, because peeling off from a living body can be preventedby adding tackifier to the bio-electrode composition or using a resinhaving good tackiness to a living body.

When the inventive bio-electrode is used as a wearable device, thecomponents such as wiring between the bio-electrode and a sensor devicemay be any material without being limited to particular ones. Forexample, it is possible to apply the ones described in JP 2004-033468A.

As described above, the inventive bio-electrode is capable of conductingelectric signals efficiently from skin to a device (i.e., excellent inelectric conductivity), free from the risk of causing allergies evenwhen it is worn on skin for a long time (i.e., excellent inbiocompatibility), light in weight, manufacturable at low cost, and freefrom large lowering of the electric conductivity even when it is wettedwith water or dried, because the living body contact layer is formedfrom a cured material of the inventive bio-electrode compositiondescribed above. It is possible to improve the electric conductivitystill more by adding a carbon material, and to manufacture a highlystretchable bio-electrode that is always in contact with skin bycombining a urethane resin that has flexibility and stretchability. Thisurethane resin, having silicon-containing groups in the side chains, hashigher repellency to repel perspiration or water to exclude theinfluences thereof, together with higher biocompatibility. Additionally,this urethane resin has improved strength since it has a urethane mainchain, exhibits higher ionic conductivity since it also has a polyethermain chain, and functions as a highly sensitive bio-electrode thereby.It is also possible to improve the stretchability and tackiness to skinby additives, and to control the stretchability and tackiness byadjusting the composition of the resin and the thickness of the livingbody contact layer appropriately. Accordingly, the inventivebio-electrode described above is particularly suitable as abio-electrode used for a medical wearable device.

<Method for Manufacturing Bio-Electrode>

The present invention also provides a method for manufacturing abio-electrode having an electro-conductive base material and a livingbody contact layer formed on the electro-conductive base material,comprising: applying the inventive bio-electrode composition describedabove onto the electro-conductive base material; and curing thebio-electrode composition; thereby forming the living body contactlayer.

Incidentally, the electro-conductive base material, the bio-electrodecomposition, etc. used for the inventive method for manufacturing abio-electrode are the same as those in the inventive bio-electrodedescribed above.

As an example of a method for manufacturing a bio-electrode of thepresent invention, it is preferable to produce a living body contactlayer based on a urethane resin by mixing a silicone-pendant diolcompound, a hydroxy group-containing compound, an ionic polymer, anelectric conductivity improver, etc., followed by mixing an isocyanatecompound. Since the curing reaction occurs when the isocyanate compoundis mixed, it is preferable to mix the isocyanate compound at the end.The living body contact layer is preferable not to have openings due tofoaming. Accordingly, it is preferable that the molar amounts of theisocyanate groups and the hydroxy groups be the same or the hydroxygroups be excess.

The bio-electrode composition can be made from a material in which ahydroxy group-containing compound, an isocyanate compound, an ionicpolymer, and an electric conductivity improver are mixed with asilicone-pendant diol compound, for example. In this case, the hydroxygroup-containing compound and the isocyanate compound may be mixed atone time or may be mixed in stages.

As the method for applying the inventive bio-electrode composition ontothe electro-conductive base material, any method can be used withoutbeing limited to particular ones; and, for example, dip coating, spraycoating, spin coating, roll coating, flow coating, doctor coating,screen printing, flexographic printing, gravure printing, and inkjetprinting are suitable.

The method for curing the bio-electrode composition can be appropriatelyselected based on a kind of resin used for the bio-electrode compositionwithout being limited to particular methods. For example, the resin ispreferably cured by either or both of heat and light. The foregoingbio-electrode composition can also be cured by adding a catalyst togenerate acid or base, which causes a crosslinking reaction.

In case of heating, the temperature may be appropriately selected basedon a kind of resin used for the bio-electrode composition without beinglimited to particular temperature. For example, it is preferable to beabout 50 to 250° C., but it is also possible to cure by leaving thecomposition at room temperature for a long time.

When the heating and light irradiation are combined, it is possible toperform the heating and the light irradiation simultaneously, to performthe heating after the light irradiation, or to perform the lightirradiation after the heating. It is also possible to perform air-dryingto evaporate solvent before heating the coating film.

As described above, the inventive method for manufacturing abio-electrode makes it possible to manufacture the inventivebio-electrode easily and at low cost, which is excellent in electricconductivity and biocompatibility, light in weight, and free from largelowering of the electric conductivity even when it is wetted with wateror dried.

EXAMPLES

Hereinafter, the present invention will be specifically described byshowing Examples and Comparative Examples, but the present invention isnot limited to the following Examples.

Ionic polymers-1 to 12 blended to solutions of bio-electrode compositionas an electro-conductive material were synthesized as follows. Each 30mass % monomer solution in PGMEA was introduced into a reaction vesseland mixed. The reaction vessel was cooled to −70° C. under a nitrogenatmosphere, and subjected to vacuum degassing and nitrogen blowingrepeated for three times. After raising the temperature to roomtemperature, azobis(isobutyronitrile) (AIBN) was added thereto as apolymerization initiator in an amount of 0.01 mole per 1 mole of thewhole monomers, this was warmed to a temperature of 60° C. and thenallowed to react for 15 hours. The composition of obtained polymer wasdetermined by ¹H-NMR after drying the solvent, and the Mw and Mw/Mn weredetermined by gel permeation chromatography (GPC) using tetrahydrofuran(THF) as a solvent.

The following are Ionic polymers-1 to 12 and Comparative Ammoniumsalts-1 to 2 each blended to the bio-electrode composition solution asan electro-conductive material.

Ionic Polymer-1

Mw=20,900

Mw/Mn=2.21

Ionic Polymer-2Mw=23,100Mw/Mn=2.01

Ionic Polymer-3Mw=27,400Mw/Mn=1.94

The number of repeating siloxane unit in the formula shows the averagevalue.Ionic Polymer-4Mw=30,600Mw/Mn=1.88

The number of repeating siloxane unit in the formula shows the averagevalue.Ionic Polymer-5Mw=26,600Mw/Mn=1.86

The number of repeating siloxane unit in the formula shows the averagevalue.Ionic Polymer-6Mw=21,900Mw/Mn=2.10

The number of repeating siloxane unit in the formula shows the averagevalue.Ionic Polymer-7Mw=35,700Mw/Mn=2.33

The number of repeating siloxane unit in the formula shows the averagevalue.Ionic Polymer-8Mw=35,700Mw/Mn=2.33

The number of repeating siloxane unit in the formula shows the averagevalue.Ionic Polymer-9Mw=33,100Mw/Mn=2.02

The number of repeating siloxane unit in the formula shows the averagevalue.Ionic Polymer-10Mw=21,500Mw/Mn=1.96

The number of repeating siloxane unit in the formula shows the averagevalue.Ionic Polymer-11Mw=24,500Mw/Mn=1.91

The number of repeating siloxane unit in the formula shows the averagevalue.Ionic Polymer-12Mw=16,300Mw/Mn=1.75

Comparative Ammonium Salts-1 and 2

The following are Silicon-containing compounds-1 to 8 each blended tothe bio-electrode composition as a raw material of the resin containinga main chain having a urethane bond and two side chains each having asilicon-containing group.

The following are Hydroxy compounds-1 to 7 each blended to thebio-electrode composition.

The numbers of repeating unit in the formulae show the average values.

The following are Isocyanate compounds-1 to 5 each blended to thebio-electrode composition.

The following are electric conductivity improvers (carbon black, carbonnanotube, Au-coated particle, and Ag-coated particle) blended to thebio-electrode composition solution as an additive.

Carbon black: DENKA BLACK HS-100 manufactured by Denka Co., Ltd.

Multilayer carbon nanotube: carbon nanotube having a diameter of 0.7 to1.1 nm and a length of 300 to 2,300 nm manufactured by Sigma-Aldrich Co.LLC.

Au-coated particle: Micropearl AU (the diameter of 3 m) manufactured bySEKISUI CHEMICAL CO. LTD.

Ag-coated particle: Ag-coated powder (the diameter of 30 μm)manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.

Examples 1 to 15, Comparative Examples 1 to 3

On the basis of each composition described in Table 1, the ionicpolymer, the hydroxy compound(s), and the additive (electricconductivity improver) were mixed and degassed, and the isocyanatecompound(s) was mixed thereto at the end to prepare each bio-electrodecomposition solution (Bio-electrode solutions-1 to 15, Comparativebio-electrode solutions-1 to 3).

TABLE 1 Electroconductive Bio-electrode material Hydroxy compoundsIsocyanate compound Additive solution (parts by mass) (parts by mass)(parts by mass) (parts by mass) Bio-electrode Ionic Silicon-containingcompound-1 (3) Isocyanate compound-1 (11) Carbon solution-1 polymer-1(4) Hydroxy compound-1 (5) black (2) Hydroxy compound-2 (2) Hydroxycompound-4 (10) Bio-electrode Ionic Silicon-containing compound-2 (5)Isocyanate compound-2 (7) Carbon solution-2 polymer-2 (6) Hydroxycompound-3 (1) black (3) Hydroxy compound-5 (15) Bio-electrode IonicSilicon-containing compound-3 (4) Isocyanate compound-3 (4) Carbonsolution-3 polymer-3 (5) Hydroxy compound-3 (1) black (2) Hydroxycompound-6 (20) Bio-electrode Ionic Silicon-containing compound-4 (5)Isocyanate compound-3 (9) Carbon solution-4 polymer-4 (5) Hydroxycompound-7 (5) black (2) Hydroxy compound-3 (1) Hydroxy compound-4 (15)Bio-electrode Ionic Silicon-containing compound-5 (3) Isocyanatecompound-3 (9) Carbon solution-5 polymer-5 (5) Hydroxy compound-7 (5)black (2) Hydroxy compound-3 (1) Hydroxy compound-4 (15) Bio-electrodeIonic Silicon-containing compound-6 (3) Isocyanate compound-3 (9) Carbonsolution-6 polymer-6 (5) Hydroxy compound-7 (5) black (2) Hydroxycompound-3 (1) Hydroxy compound-4 (15) Bio-electrode IonicSilicon-containing compound-7 (3) Isocyanate compound-3 (9) Carbonsolution-7 polymer-7 (5) Hydroxy compound-7 (5) black (2) Hydroxycompound-3 (1) Hydroxy compound-4 (15) Bio-electrode IonicSilicon-containing compound-8 (3) Isocyanate compound-3 (9) Carbonsolution-8 polymer-8 (5) Hydroxy compound-7 (5) black (2) Hydroxycompound-3 (1) Hydroxy compound-4 (15) Bio-electrode IonicSilicon-containing compound-1 (5) Isocyanate compound-4 (1) Carbonsolution-9 polymer-6 (6) Hydroxy compound-4 (18) Isocyanate compound-3(2) black (2) Bio-electrode Ionic Silicon-containing compound-1 (5)Isocyanate compound-4 (1) Carbon solution-10 polymer-7 (6) Hydroxycompound-4 (18) Isocyanate compound-3 (2) black (2) Bio-electrode IonicSilicon-containing compound-1 (5) Isocyanate compound-4 (1) Carbonsolution-11 polymer-8 (6) Hydroxy compound-4 (18) Isocyanate compound-3(2) black (2) Bio-electrode Ionic Silicon-containing compound-1 (5)Isocyanate compound-4 (1) Multilayer solution-12 polymer-9 (6) Hydroxycompound-4 (18) Isocyanate compound-3 (2) carbon nanotube (2)Bio-electrode Ionic Silicon-containing compound-1 (5) Isocyanatecompound-4 (1) Ag-coated solution-13 polymer-10 (6) Hydroxy compound-4(18) Isocyanate compound-3 (2) particle (6) Bio-electrode IonicSilicon-containing compound-1 (5) Isocyanate compound-4 (1) Au-coatedsolution-14 polymer-11 (8) Hydroxy compound-4 (18) Isocyanate compound-3(2) particle (6) Bio-electrode Ionic Silicon-containing compound-1 (5)Isocyanate compound-5 (1) Carbon solution-15 polymer-12 (2) Hydroxycompound-4 (18) Isocyanate compound-3 (2) black (2) ComparativeComparative Silicon-containing compound-1 (5) Isocyanate compound-4 (1)Carbon bio-electrode ammonium Hydroxy compound-4 (18) Isocyanatecompound-3 (2) black (2) solution-1 salt-1 (2) Comparative ComparativeSilicon-containing compound-1 (5) Isocyanate compound-4 (1) Carbonbio-electrode ammonium Hydroxy compound-4 (18) Isocyanate compound-3 (2)black (2) solution-2 salt-2 (2) Comparative Ionic Hydroxy compound-1 (5)Isocyanate compound-1 (10) Carbon bio-electrode polymer-1 (4) Hydroxycompound-2 (2) black (2) solution-3 Hydroxy compound-4 (10)(Evaluation of Electric Conductivity)

Each bio-electrode solution was applied onto an aluminum disk having adiameter of 3 cm and a thickness of 0.2 mm by using an applicator. Thiswas baked at 100° C. for 60 minutes under a nitrogen atmosphere by usingan oven to be cured, thereby producing four pieces of bio-electrodes foreach bio-electrode composition solution. Thus obtained bio-electrode wasprovided with the living body contact layer 3 at one side and providedwith the aluminum disk 8 at the other side as an electro-conductive basematerial as shown in FIGS. 3(a) and (b). Then, the copper wiring 9 waspasted on the surface of the aluminum disk 8 with self-adhesive tape atthe side that had not been coated with the living body contact layer toform a lead-out electrode, which was connected to an impedancemeasurement apparatus as shown in FIG. 3 (b). Two pieces of thebio-electrodes 1′ were pasted on a human arm at a distance of 15 cm fromeach other such that the side of each living body contact layer was incontact with the skin as shown in FIG. 4. The initial impedance wasmeasured while altering the frequency by using an AC impedancemeasurement apparatus SI1260 manufactured by Solartron. Then, theremained two pieces of the bio-electrodes were immersed in pure waterfor 1 hour, and used for measuring the impedance on skin by the samemethod described above immediately after the immersion. Each impedanceat the frequency of 1,000 Hz is shown in Table 2.

(Measurement of Thickness and Contact Angle of Living Body ContactLayer)

On each bio-electrode produced in the evaluation test of electricconductivity described above, the thickness of the living body contactlayer was measured by using a micrometer. The contact angle with waterof the surface of each living body contact layer was measured by using acontact angle meter. The results are shown in Table 2.

TABLE 2 Initial Impedance Thickness Contact imped- after waterBio-electrode of resin angle ance immersion Example solution (μm) (°)(Ω) (Ω) Example 1 Bio-electrode 520 103 3.8E⁴ 3.5E⁴ solution-1 Example 2Bio-electrode 510 104 5.5E⁴ 6.0E⁴ solution-2 Example 3 Bio-electrode 47098 1.2E⁴ 1.3E⁴ solution-3 Example 4 Bio-electrode 460 103 8.8E³ 8.5E³solution-4 Example 5 Bio-electrode 440 102 8.6E⁴ 7.5E⁴ solution-5Example 6 Bio-electrode 490 103 6.5E⁴ 7.1E⁴ solution-6 Example 7Bio-electrode 510 98 5.5E⁴ 5.3E⁴ solution-7 Example 8 Bio-electrode 500103 6.0E³ 7.1E³ solution-8 Example 9 Bio-electrode 530 102 7.2E⁴ 7.1E⁴solution-9 Example 10 Bio-electrode 510 104 6.2E⁴ 7.3E⁴ solution-10Example 11 Bio-electrode 530 103 6.4E⁴ 5.9E⁴ solution-11 Example 12Bio-electrode 520 103 2.2E³ 2.5E³ solution-12 Example 13 Bio-electrode710 104 9.2E⁴ 9.3E⁴ solution-13 Example 14 Bio-electrode 700 103 9.4E⁴9.9E⁴ solution-14 Example 15 Bio-electrode 480 103 7.2E⁴ 7.5E⁴solution-15 Comparative Comparative 510 103 5.2E⁴ 8.3E⁶ Example 1bio-electrode solution-1 Comparative Comparative 520 103 6.2E⁴ 8.9E⁶Example 2 bio-electrode solution-2 Comparative Comparative 520 70 5.1E⁴2.3E³ Example 3 bio-electrode solution-3

As shown in Table 2, each of Examples 1 to 15, in which the inventiveliving body contact layer was formed, exhibited higher contact anglewith water and lower initial impedance, without causing large increaseof impedance by an order of magnitude after the water immersion anddrying. That is, Examples 1 to 15 each gave a bio-electrode with higherinitial electric conductivity without causing large change of theelectric conductivity when it was wetted with water or dried.

On the other hand, each of Comparative Examples 1 and 2, in which theliving body contact layer was formed using a bio-electrode solutioncontaining a previous salt, caused large increase of the impedance suchthat the order of magnitude was changed after water immersion and dryingalthough the initial impedance was low. That is, each of ComparativeExamples 1 and 2 only gave a bio-electrode in which the electricconductivity largely lowered when it was wetted with water or driedalthough the initial electric conductivity was high. Comparative Example3, in which silicone-pendant urethane was not contained whereas an ionicpolymer was contained, exhibited lower contact angle with water, thatis, higher hydrophilicity. As a result, the bio-electrode was soakedwith water after water immersion to lower the impedance, causing aresult that the impedance was changed due to an influence of water.

As described above, it was revealed that the bio-electrode, with theliving body contact layer being formed by using the inventivebio-electrode composition, was excellent in electric conductivity,biocompatibility, and adhesion properties to an electro-conductive basematerial; excellent in holding the electro-conductive materials such asan ionic polymer and carbon black to prevent large lowering of electricconductivity even when it was wetted with water and dried; light inweight, and manufacturable at low cost.

It is to be noted that the present invention is not restricted to theforegoing embodiment. The embodiment is just an exemplification, and anyexamples that have substantially the same feature and demonstrate thesame functions and effects as those in the technical concept describedin claims of the present invention are included in the technical scopeof the present invention.

The invention claimed is:
 1. A bio-electrode composition comprising: aresin containing a main chain having a urethane moiety and two sidechains each having a silicon-containing group; and an electro-conductivematerial, wherein the electro-conductive material is a polymer compoundhaving one or more fragments selected from the group consisting offluorosulfonic acid salts shown by the following formulae (1)-1 and(1)-2, sulfonimide salts shown by the following formula (1)-3, andsulfonamide salts shown by the following formula (1)-4,

wherein Rf₁ and Rf₂ each represent a hydrogen atom, a fluorine atom, atrifluoromethyl group, or an oxygen atom, provided that when Rf₁represents an oxygen atom, Rf₂ also represents an oxygen atom to form acarbonyl group together with a carbon atom bonded therewith; Rf₃ and Rf₄each represent a hydrogen atom, a fluorine atom, or a trifluoromethylgroup; provided that one or more fluorine atoms are contained in Rf₁ toRf₄; Rf₅, Rf₆, and Rf₇ each represent a fluorine atom, or a linear orbranched alkyl group having 1 to 4 carbon atoms, provided that one ormore fluorine atoms are contained; X⁺ represents a sodium ion, apotassium ion, or a cation having an ammonium ion structure shown by thefollowing formula (1)-5; and “m” is an integer of 1 to 4,

wherein R¹ to R⁴ each represent a hydrogen atom, a linear, branched, orcyclic alkyl group having 1 to 20 carbon atoms, an alkenyl group having2 to 14 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms,optionally having an ether group, an ester group, a carbonyl group, asulfonyl group, a cyano group, an amino group, a nitro group, hydroxygroup, a sulfur atom except in the sulfonyl group, or a halogen atom,and optionally bonded to each other to form a ring.
 2. The bio-electrodecomposition according to claim 1, wherein the one or more fragments arepresent in one or more repeating units selected from repeating units a1to a7 shown by the following formulae (2),

wherein R⁵, R⁷, R⁹, R¹², R¹⁴, R¹⁵, and R¹⁷ each independently representa hydrogen atom or a methyl group; R⁶, R⁸, R¹⁰, R¹³ and R¹⁶ eachindependently represent any of a single bond, an ester group, or alinear, branched, or cyclic hydrocarbon group having 1 to 13 carbonatoms optionally having either or both of an ether group and an estergroup; R¹¹ represents a linear or branched alkylene group having 1 to 4carbon atoms, and one or two of the hydrogen atoms in R¹¹ are optionallysubstituted with a fluorine atom; Z₁, Z₂, Z₃, Z₄, and Z₆ eachindependently represent any of a single bond, a phenylene group, anaphthylene group, an ether group, an ester group, or an amide group; Z₅represents any of a single bond, an ether group, or an ester group; Z₇represents a single bond, an arylene group having 6 to 12 carbon atoms,or —C(═O)—O—Z⁸—; and Z⁸ represents a linear, branched, or cyclicalkylene group having 1 to 12 carbon atoms, or a divalent aromatichydrocarbon group having 6 to 10 carbon atoms, optionally having anether group, a carbonyl group, or an ester group in Z⁸; Y represents anoxygen atom or an —NR¹⁸— group; R¹⁸ represents a hydrogen atom, or alinear or branched alkyl group having 1 to 4 carbon atoms, optionallybonded to R⁸ to form a ring; “m” is an integer of 1 to 4; a1, a2, a3,a4, a5, a6, and a7 satisfy 0≤a1≤1.0, 0≤a2≤1.0, 0≤a3≤1.0, 0<a4<1.0,0<a5<1.0, 0≤a6≤1.0, 0≤a7≤1.0, and 0<a1+a2+a3+a4+a5+a6+a7≤1.0; and Rf₅,Rf₆, Rf₇, and X⁺ have the same meanings as defined above.
 3. Thebio-electrode composition according to claim 1, wherein theelectro-conductive material is a polymer compound having a repeatingunit containing a sulfonamide salt shown by the formula (1)-4.
 4. Thebio-electrode composition according to claim 1, wherein the resincontaining a main chain having a urethane moiety and two side chainseach having a silicon-containing group has a structure shown by thefollowing formula (3),

wherein R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ each represent a linear,branched, or cyclic alkyl group having 1 to 6 carbon atoms, a phenylgroup, a 3,3,3-trifluoropropyl group, or a group shown by—(OSiR²⁵R²⁶)_(n)—OSiR²⁷R²⁸R²⁹; R²⁵, R²⁶, R²⁷, R²⁸, and R²⁹ have the samemeanings as R¹⁹ to R²⁴; “n” is a number in a range of 0 to 100; “A”represents a linear or branched alkylene group having 1 to 4 carbonatoms; and X represents a methylene group or an ether group.
 5. Thebio-electrode composition according to claim 2, wherein the resincontaining a main chain having a urethane moiety and two side chainseach having a silicon-containing group has a structure shown by thefollowing formula (3),

wherein R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ each represent a linear,branched, or cyclic alkyl group having 1 to 6 carbon atoms, a phenylgroup, a 3,3,3-trifluoropropyl group, or a group shown by—(OSiR²⁵R²⁶)_(n)—OSiR²⁷R²⁸R²⁹; R²⁵, R²⁶, R²⁷, R²⁸, and R²⁹ have the samemeanings as R¹⁹ to R²⁴; “n” is a number in a range of 0 to 100; “A”represents a linear or branched alkylene group having 1 to 4 carbonatoms; and X represents a methylene group or an ether group.
 6. Thebio-electrode composition according to claim 3, wherein the resincontaining a main chain having a urethane moiety and two side chainseach having a silicon-containing group has a structure shown by thefollowing formula (3),

wherein R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ each represent a linear,branched, or cyclic alkyl group having 1 to 6 carbon atoms, a phenylgroup, a 3,3,3-trifluoropropyl group, or a group shown by—(OSiR²⁵R²⁶)_(n)—OSiR²⁷R²⁸R²⁹; R²⁵, R²⁶, R²⁷, R²⁸, and R²⁹ have the samemeanings as R¹⁹ to R²⁴; “n” is a number in a range of 0 to 100; “A”represents a linear or branched alkylene group having 1 to 4 carbonatoms; and X represents a methylene group or an ether group.
 7. Thebio-electrode composition according to claim 1, wherein the resincontaining a main chain having a urethane moiety and two side chainseach having a silicon-containing group has a structure containing apolyether main chain shown by the following formula (4),

wherein R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ each represent a linear,branched, or cyclic alkyl group having 1 to 6 carbon atoms, a phenylgroup, a 3,3,3-trifluoropropyl group, or a group shown by—(OSiR²⁵R²⁶)_(n)—OSiR²⁷R²⁸R²⁹; R²⁵, R²⁶, R²⁷, R²⁸, and R²⁹ have the samemeanings as R¹⁹ to R²⁴; “n” is a number in a range of 0 to 100; “A”represents a linear or branched alkylene group having 1 to 4 carbonatoms; X represents a methylene group or an ether group; R³⁰ represent alinear, branched, or cyclic alkylene group having 2 to 12 carbon atoms;and “v” and “w” satisfy 0<v<1.0, 0<w<1.0, and 0<v+w≤1.0.
 8. Thebio-electrode composition according to claim 2, wherein the resincontaining a main chain having a urethane moiety and two side chainseach having a silicon-containing group has a structure containing apolyether main chain shown by the following formula (4),

wherein R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ each represent a linear,branched, or cyclic alkyl group having 1 to 6 carbon atoms, a phenylgroup, a 3,3,3-trifluoropropyl group, or a group shown by—(OSiR²⁵R²⁶)_(n)—OSiR²⁷R²⁸R²⁹; R²⁵, R²⁶, R²⁷, R²⁸, and R²⁹ have the samemeanings as R¹⁹ to R²⁴; “n” is a number in a range of 0 to 100; “A”represents a linear or branched alkylene group having 1 to 4 carbonatoms; X represents a methylene group or an ether group; R³⁰ represent alinear, branched, or cyclic alkylene group having 2 to 12 carbon atoms;and “v” and “w” satisfy 0<v<1.0, 0<w<1.0, and 0<v+w≤1.0.
 9. Thebio-electrode composition according to claim 3, wherein the resincontaining a main chain having a urethane moiety and two side chainseach having a silicon-containing group has a structure containing apolyether main chain shown by the following formula (4),

wherein R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ each represent a linear,branched, or cyclic alkyl group having 1 to 6 carbon atoms, a phenylgroup, a 3,3,3-trifluoropropyl group, or a group shown by—(OSiR²⁵R²⁶)_(n)—OSiR²⁷R²⁸R²⁹; R²⁵, R²⁶, R²⁷, R²⁸, and R²⁹ have the samemeanings as R¹⁹ to R²⁴; “n” is a number in a range of 0 to 100; “A”represents a linear or branched alkylene group having 1 to 4 carbonatoms; X represents a methylene group or an ether group; R³⁰ represent alinear, branched, or cyclic alkylene group having 2 to 12 carbon atoms;and “v” and “w” satisfy 0<v<1.0, 0<w<1.0, and 0<v+w≤1.0.
 10. Thebio-electrode composition according to claim 1, wherein the resincontaining a main chain having a urethane moiety and two side chainseach having a silicon-containing group is a reaction product of a diolcompound shown by the following formula (5), a polyether compound havinga hydroxy group at the terminal, and a compound having an isocyanategroup,

wherein R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ each represent a linear,branched, or cyclic alkyl group having 1 to 6 carbon atoms, a phenylgroup, a 3,3,3-trifluoropropyl group, or a group shown by—(OSiR²⁵R²⁶)_(n)—OSiR²⁷R²⁸R²⁹; R²⁵, R²⁶, R²⁷, R²⁸, and R²⁹ have the samemeanings as R¹⁹ to R²⁴; “n” is a number in a range of 0 to 100; “A”represents a linear or branched alkylene group having 1 to 4 carbonatoms; and X represents a methylene group or an ether group.
 11. Thebio-electrode composition according to claim 1, further comprising anorganic solvent.
 12. The bio-electrode composition according to claim 1,further comprising a carbon material.
 13. The bio-electrode compositionaccording to claim 12, wherein the carbon material is either or both ofcarbon black and carbon nanotube.
 14. A bio-electrode comprising anelectro-conductive base material and a living body contact layer formedon the electro-conductive base material; wherein the living body contactlayer is a cured material of the bio-electrode composition according toclaim
 1. 15. The bio-electrode according to claim 14, wherein theelectro-conductive base material comprises one or more species selectedfrom gold, silver, silver chloride, platinum, aluminum, magnesium, tin,tungsten, iron, copper, nickel, stainless steel, chromium, titanium, andcarbon.
 16. A method for manufacturing a bio-electrode having anelectro-conductive base material and a living body contact layer formedon the electro-conductive base material, comprising: applying thebio-electrode composition according to claim 1 onto theelectro-conductive base material; and curing the bio-electrodecomposition; thereby forming the living body contact layer.
 17. Themethod for manufacturing a bio-electrode according to claim 16, whereinthe electro-conductive base material comprises one or more speciesselected from gold, silver, silver chloride, platinum, aluminum,magnesium, tin, tungsten, iron, copper, nickel, stainless steel,chromium, titanium, and carbon.